Try subscribing to this issue鈥檚 closure, it takes 4 clicks. Can this be reduced to 1 click?
Examples:

Or 3 clicks 馃槵 (but nearer/easier)

Dropdown demo code
<details class="details-reset details-overlay" open="">
<summary aria-haspopup="true" class="btn btn-block btn-sm thread-subscribe-button">
{unmuteIcon()} Subscribe
</summary>
<div class="SelectMenu right-0">
<div class="SelectMenu-modal">
<header class="SelectMenu-header">
<h3 class="SelectMenu-title">Customize</h3>
<button class="SelectMenu-closeButton" type="button">
{xIcon()}
</button>
</header>
<div class="SelectMenu-list">
<button class="SelectMenu-item" role="menuitemcheckbox">
{checkIcon()} Unsubscribed
</button>
<button class="SelectMenu-item" role="menuitemcheckbox">
{checkIcon()} All notifications
</button>
<button class="SelectMenu-item" role="menuitemcheckbox">
{checkIcon()} Merged
</button>
<button class="SelectMenu-item" role="menuitemcheckbox">
{checkIcon()} Closed
</button>
<button class="SelectMenu-item" role="menuitemcheckbox">
{checkIcon()} Reopened
</button>
</div>
</div>
</div>
</details>
Keeping the "Custom" section always open would also bring it down to 3 clicks:

I think a relatively-easy compromise would be to add a button that subscribes you to status changes only (closed, merged, reopened) in one click

At the very least, it can just exist and be able to submit the form.
As an improvement, it could show a pressed+disabled style if the current subscription settings are exactly merged, closed, reopened
Any other options and the ability to undo this are available in the Customize modal anyway.
Most helpful comment
I think a relatively-easy compromise would be to add a button that subscribes you to status changes only (closed, merged, reopened) in one click
At the very least, it can just exist and be able to submit the form.
As an improvement, it could show a pressed+disabled style if the current subscription settings are exactly
merged, closed, reopenedAny other options and the ability to undo this are available in the Customize modal anyway.