Since the preset underneath was a bit resonant, I thought perhaps it was blowing the output over 0dBFS and that was the problem, so I turned the master volume down, but even at 0 on that control it was still doing it.
So I figured that I'd save the preset so I could upload it for you (kv331) to see if there was an obvious cause, removed my full name from the preset info realising that I'd be doxxing myself if I didn't (since I intended to post a link here), and re-saved.
At that point when I went to switch presets to verify it loaded the preset information properly, I saw that the 'recent presets' list was corrupt (see below image). Incidentally there is no preset called 'RickMort', there is a standard preset called 'SEQ RickMort' but that's not the same string is it...
Removing the plugin and reloading it, and then reloading the saved preset indicated no problem with the auto-mute kicking in, and the recent presets list was restored to working normally, similarly the preset now sounded just fine, as if the problem had never happened.
Since this is likely just SM having some weird edge case that caused it to get confused, I'm not really expecting much can be done, perhaps it was just a random cosmic ray flipping a bit in memory and not even a SM issue, who knows, but I felt I should probably document it a little in case it happens again to someone else, or whatever.
Corrupt 'recent presets' list:
Preset file (I doubt this contains any usable information, as it loads just fine once SM was reloaded, but who knows, maybe there's some hint at corruption somewhere in the bits):
https://we.tl/t-H6nicgjsrK
(For any 3rd party, it's not that useful/interesting a preset and didn't sound right timing-wise once the Arp was working sanyway)
