After upgrade to 3.0.1 I get the following error:
Warning: Undefined array key "back_to_top_speed" in back_to_top_page_attachments() (line 35 of /app/web/modules/contrib/back_to_top/back_to_top.module)
#0 /app/web/core/includes/bootstrap.inc(166): _drupal_error_handler_real(2, 'Undefined array...', '/app/web/module...', 35)
#1 /app/web/modules/contrib/back_to_top/back_to_top.module(35): _drupal_error_handler(2, 'Undefined array...', '/app/web/module...', 35)
#2 /app/web/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(311): back_to_top_page_attachments(Array)
#3 /app/web/core/lib/Drupal/Core/Extension/ModuleHandler.php(395): Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}(Object(Closure), 'back_to_top')
#4 /app/web/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(308): Drupal\Core\Extension\ModuleHandler->invokeAllWith('page_attachment...', Object(Closure))
#5 /app/web/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(285): Drupal\Core\Render\MainContent\HtmlRenderer->invokePageAttachmentHooks(Array)
#6 /app/web/core/lib/Drupal/Core/Render/Renderer.php(638): Drupal\Core\Render\MainContent\HtmlRenderer->Drupal\Core\Render\MainContent\{closure}()
#7 /app/web/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(284): Drupal\Core\Render\Renderer->executeInRenderContext(Object(Drupal\Core\Render\RenderContext), Object(Closure))
#8 /app/web/core/lib/Drupal/Core/Render/MainContent/HtmlRenderer.php(128): Drupal\Core\Render\MainContent\HtmlRenderer->prepare(Array, Object(Symfony\Component\HttpFoundation\Request), Object(Drupal\Core\Routing\CurrentRouteMatch))
#9 /app/web/core/lib/Drupal/Core/EventSubscriber/MainContentViewSubscriber.php(90): Drupal\Core\Render\MainContent\HtmlRenderer->renderResponse(Array, Object(Symfony\Component\HttpFoundation\Request), Object(Drupal\Core\Routing\CurrentRouteMatch))
#10 [internal function]: Drupal\Core\EventSubscriber\MainContentViewSubscriber->onViewRenderArray(Object(Symfony\Component\HttpKernel\Event\ViewEvent), 'kernel.view', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher))
#11 /app/web/core/lib/Drupal/Component/EventDispatcher/ContainerAwareEventDispatcher.php(111): call_user_func(Array, Object(Symfony\Component\HttpKernel\Event\ViewEvent), 'kernel.view', Object(Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher))
#12 /app/vendor/symfony/http-kernel/HttpKernel.php(186): Drupal\Component\EventDispatcher\ContainerAwareEventDispatcher->dispatch(Object(Symfony\Component\HttpKernel\Event\ViewEvent), 'kernel.view')
#13 /app/vendor/symfony/http-kernel/HttpKernel.php(76): Symfony\Component\HttpKernel\HttpKernel->handleRaw(Object(Symfony\Component\HttpFoundation\Request), 1)
#14 /app/web/core/lib/Drupal/Core/StackMiddleware/Session.php(53): Symfony\Component\HttpKernel\HttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#15 /app/web/core/lib/Drupal/Core/StackMiddleware/KernelPreHandle.php(48): Drupal\Core\StackMiddleware\Session->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#16 /app/web/core/lib/Drupal/Core/StackMiddleware/ContentLength.php(28): Drupal\Core\StackMiddleware\KernelPreHandle->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#17 /app/web/core/modules/big_pipe/src/StackMiddleware/ContentLength.php(32): Drupal\Core\StackMiddleware\ContentLength->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#18 /app/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(191): Drupal\big_pipe\StackMiddleware\ContentLength->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#19 /app/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(128): Drupal\page_cache\StackMiddleware\PageCache->fetch(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#20 /app/web/core/modules/page_cache/src/StackMiddleware/PageCache.php(82): Drupal\page_cache\StackMiddleware\PageCache->lookup(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#21 /app/web/core/lib/Drupal/Core/StackMiddleware/ReverseProxyMiddleware.php(48): Drupal\page_cache\StackMiddleware\PageCache->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#22 /app/web/core/lib/Drupal/Core/StackMiddleware/NegotiationMiddleware.php(51): Drupal\Core\StackMiddleware\ReverseProxyMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#23 /app/web/core/lib/Drupal/Core/StackMiddleware/AjaxPageState.php(36): Drupal\Core\StackMiddleware\NegotiationMiddleware->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#24 /app/web/core/lib/Drupal/Core/StackMiddleware/StackedHttpKernel.php(51): Drupal\Core\StackMiddleware\AjaxPageState->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#25 /app/web/core/lib/Drupal/Core/DrupalKernel.php(741): Drupal\Core\StackMiddleware\StackedHttpKernel->handle(Object(Symfony\Component\HttpFoundation\Request), 1, true)
#26 /app/web/index.php(19): Drupal\Core\DrupalKernel->handle(Object(Symfony\Component\HttpFoundation\Request))
#27 {main}