they did that to mee too luckily I can bypass it. totally understand it is very dumb๐ญ
there might be some interference around you, dirty connections, or some bad wiring in the amp, not sure though, I use a Fender Spider II Line 6 amp. Used to have a Marshall, not sure what kind, but I sold that. Wasn't the right amp for me. But yeah I recommend checking to see if the connections are dirty, any electromagnetic interference around you, and if it comes down to it, check the internals of the amp.
Not an expert in amp maintenance just so you know. Also if all else fails you should probably take it to a guitar shop or something.
@the-when Funny I did take the guitar to a tech who said it looked fine (they tightened the input jack), but did mention LED light interface, which I do have several of in the room. I should test by playing in a different room. Thanks for the info.
:3