The chromium-ffmpeg snap at that point would already provide five different versions of the FFMPEG library, I dropped the older ones unaware that Vivaldi could potentially still use it. I’m sorry for that mistake, for years Opera was the only consumer, old habits die hard. ):
Could you send us an email message so we include you in the loop when new releases are due (or at least when old versions are dropped)? You can contact the Chromium Team administrators via Launchpad or just send me an email ({my user ID}@ubuntu.com) and I’ll include them as needed.
Checking with you before dropping a FFMPEG version, as well as simply not dropping it, is no problem on our side; the cleanup is only done to save build resources and time (space issues in the builders have been worked around). You don’t need to change what is already working for you.
Meanwhile I just submitted a build to bring back 115016 and 115541 and will release it to stable as soon as it is ready. Sorry for the inconvenience!