Seems all of our default muse form widgets are doing the same. Whenever you try and hit submit they say, "The server encountered an error". This is on any of our clients sites that use the default contact form.
I branched out your discussion because it's altogether a different issue.
Since when you are observing this issue?, Have you made any recent changes in the site before this error started showing up?
Can you please share the affected site URLs with me for further testing?
Had something to do with the reCAPTCHA V2. Forms work fine without it.