The suggestion is the same as the flagged word:
Besides, if I manually change to “analyze”, LO flags it as wrong spelling.
In en-gb there are 2 rulegroups is/iz spellings. De-select the rulegroup OXFORD_SPELLING_IZE (we [me and @tiagosantos] are keeping the rule temporarily for testing.)
Oh actually, I like to keep the rule on. Just pointing out a bug.