While oral antibiotics can actually cause remissions, data also shows that antibiotics can disturb the microbial ecosystem to such an extent that pathogenic bacteria can gain the upper hand in crohn's disease patients. This happens during the "post-antibiotic" period, especially if broad-spectrum antibiotics where used.
In theory, people with crohn's disease should be offered intravenous antibiotics or topical applications for secondary infections, instead of oral antibiotics. Of course this is not always possible, especially not with the pandemic which complicates things.