It looks good to me:

I tested it with Firefox 78.7.0esr, but I can’t reproduce it with 86.0b6 (Developer Edition) either. (Both have English (US) locale.)

Could you post a direct link to an example message for testing?

The message seen on the screenshots of both of us is m:Translations:Tech/News/2021/06/47/he.

I cannot reproduce it either (78.7.0esr on Linux). A bug with the nightly release?

In T279285#6972830, @Tacsipacsi wrote:

This looks like an upstream Firefox bug. The padding is still there (screenshot from version 88.0b6), and the same page still looks good in Firefox 78.9.0esr.

In T274040#6811970, @Nikerabbit wrote:

Could you post a direct link to an example message for testing?

Link:
https://meta.wikimedia.org/w/index.php?title=Special:Translate&group=page-User%3ATimur+Vorkul+%28WMDE%29%2FSuggested+values+announcement&language=bn&action=page&filter=
Snip:

Has anyone checked if this bug has been reported to Firefox?

In T274040#7020097, @R4356th wrote:

this is making translating big strings using the translation interface impossible.

I think adding a blank line at the end should work this bug around. When saving the Translations-namespace page, this blank line is dropped, and I hope it’s dropped in the actual translatable page as well. However, I couldn’t test this, because…

In T274040#7020265, @Nikerabbit wrote:

Has anyone checked if this bug has been reported to Firefox?

I think I’ve tried it, but searching in Bugzilla is a nightmare for me. I found nothing either because there is really no such bug, or because I just failed to find it. Anyways, it seems to work again in 89.0b1 (Developer Edition), so if everything goes well, it should land in stable Firefox on June 1. If adding blank lines doesn’t work for some reason, you can download Beta or Developer Edition for the time being.

In T274040#7022477, @Tacsipacsi wrote:

In T274040#7020097, @R4356th wrote:

this is making translating big strings using the translation interface impossible.

I think adding a blank line at the end should work this bug around. When saving the Translations-namespace page, this blank line is dropped, and I hope it’s dropped in the actual translatable page as well. However, I couldn’t test this, because…

That part is not clickable.

I can no longer see it in Firefox v90 2021-05-11.

Another report of this being fixed in Firefox 89. Can we close this ticket?

Firefox v78 (affected) is an ESR version. The next ESR version is v91 to be released end of July 2021, to supersede v78.

No, Firefox 78 is unaffected, affected ones seem to be only 87 and 88. Fortunately neither of these is ESR, so stable release users who have installed the now 11-day-old v89 are no longer affected, while ESR users weren’t and won’t be affected at all.

Ah thanks, I misinterpreted T274040#6811452. In that case I'd say let's decline this task?

Or close with any other status. It’s not exactly declined, since there was a valid issue, which has been fixed, just not by us and without us reporting it.