MPIV isn't properly showing up on a Mastodon web client anymore

[em-ex]

The default Mastodon web client update 4.2.x brought this strange issue where MPIV's viewer box is being rendered way below viewport.

Steps to reproduce the bug

1. Open a Mastodon instance web client, for example this random post
2. Hover over a photo
3. No MPIV viewer is visible but th e vertical scrollbar jumps, proving that the MPIV is functioning. If you keep zooming in, just the upper third of the viewer will appear on the bottom of the screen, while the remaining two thirds will still be hidden somewhere below the viewport.

Expected behavior

MPIV opens its viewer in the middle of the viewport

Environment

• Browser: Firefox 121.0.1 + Tampermonkey 5.0.1
• MPIV Version: 1.2.34

I'd really appreciate any advice on how to debug this. Thank you

[tophf]

The site unusually forbids inline style attribute via CSP header. I'll try to come up with a workaround.

[em-ex]

Thanks for the quick response!
This is strange about the CSP as my custom Stylus rules are being applied and MPIV is being injected into the page DOM.
I'd expect those not to work at all if CSP was the culprit.
Am I missing something?

[tophf]

The CSP error for mpiv's style attribute is shown in devtools console. Stylus doesn't use inline style attribute. As a workaround you can try adding a different @sandbox mode.

[em-ex]

I can confirm: adding // @sandbox JavaScript to the script code does solve the issue.
Suitable as a workaround, but would love to see if it can be solved without monkey-patching.
Thank you once again!