Enabling notify on custom comment types breaks comment form for some accounts

Disclaimer: this is an odd one. I'm not 100% sure I have the steps to reproduce right.

At the moment, it appears I had some fact confused before, because what I observe is:
* Custom content type node created by non-user1, custom comment type, with notify enabled:
- non-user1 sees the comment form normally, along with the 'notify me when...' checkbox
- user1 does not get the comment form or the 'notify me when...' checkbox
- (user1 sees comment form normally on nodes with non-custom comment type, along with the 'notify me...' checkbox)

* Custom content type node created by user1, custom comment type, with notify enabled:
- non-user1 sees the comment form normally, along with the notify checkbox
- user 1 does not get the comment form or notify checkbox
- (user 1 sees comment form normally on nodes with non-custom comment type, as well as the 'notify me' checkbox)

Not tested on a fresh Drupal 9 build.

Tested for conflicts with permissions modules: uninstalled Field Permissions module, Node View Permissions module, View Unpublished module rebuilt permissions. No observable change.

Also tested: switching theme to Olivero. The problem exists there as well.

Probably worth noting: when I look at the page code for a page lacking the comment form, I do see "notify me when..." string in the code... but so far I can't make any sense of it.

After more testing: some accounts see the form and some don't. User1 seems to be consistently not getting the form load.
Other accounts... I can't see any pattern to it after a lot of messing with roles and permissions, etc.
Two accounts with identical permissions get different results.

I am not able to reproduce the issue on a new 9.5.7 'standard' install, everything default, + this module and 1 custom comment type. There may be a conflict with some other module. Planning to test further.

I am able reproduce in a new install.

TLDR: disabling the "Replies to my comment" checkbox at admin/config/people/comment_notify causes the comment form to fail to load on nodes with the custom comment type.

Steps to reproduce:
Standard install of 9.5.7
Create custom comment type
On the Basic page content type, add a new field for comments of the custom type
Install comment_notify via composer and enable (and token comes along as a requirement)
At admin/config/people/comment_notify, check the box for the custom comment type
Create test nodes for Article and Basic page
Verify that comment form loads normally for both the default comment tupe (on Article) and the custom type (on Page)
Return to admin/config/people/comment_notify and uncheck "Replies to my comment"
Return to test node of the Basic Page type: the comment form fails to load

Hi aharown07,

I've updated the issue title and summary to reflect what you're reporting.

I followed your steps but could not recreate the issue. This is using Drupal 10.1.5 with the Olivero theme and Comment Notify 8.x-1.x-dev. Can you double check your steps and adjust the steps to recreate as necessary?