Why Are Cuts Appearing on the Tomatoes That I’m Growing in a Pot?

Question

Plant looks healthy, and the yield has been good but all the tomatoes so far yielded have cuts all around the stem that’s bearing them. These cuts become deeper as the tomatoes mature.

Answer 1

This may help:
https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-blossom-rot.htm
and this:
https://www.gardeningknowhow.com/edible/vegetables/tomato/tomato-diseases.htm