Plural endings for words ending in -is
Words ending in "is" often have an "es" plural. Analysis, hypothesis, crisis etc. Like one thesis, many theses.
The pronunciation for the ending of the words is something like:
thesis - /ɪs/
theses - /iːz/
I learnt that as a sort of rule, at least for Greek-derived words.
But I am starting to hear a lot of plurals pronounced that way even if they have nothing to do with Greek, and also when they don't even have the "-is" ending in the singular.
Example: one process, two processes
According to the rules I learnt it should be process/ɪs/, but people say process/iːz/
Same with biases. I think it should be bias/ɪz/ but I swear to god people say bias/iːz/
Are those people just being extremely pretentious like "I am very educated so I say it like a Greek word" even when they're not Greek words, or is my rule wrong?