Probable, comfortable

[Words]

Instead of probably, comfortably, etc. I am noticing this error very frequently at thé moment.

Do you hear it as well as see it written? If it's written it could be a typing mistake although e and y are not that close on a keyboard

No written only. I think people see the e on the end and sound it in their head as a y.

A bit like ' I text him yesterday' because thé t sounds vaguely like a d.

I understand what you mean. Comfortabl...e.

Yes exactly

used in the way “likely” is ?
e.g. “a probable outcome”. I thought that was correct.
Or do people say “I will probable visit my mum at the weekend “ ?

I will,probable visit my Mum at the weekend.
The first as you say is correct

I saw unbelievable instead of unbelievably today.

I've seen comfortable instead of comfortably today, in an otherwise very good post. Could it be that a kind of predictive text is grabbing it and the poster isn't noticing the ending because she's gone on to the next word?

Unbelievable instead of unbelievably also today.