As far as I understand, each time I delete the call, all fields of the "new QSO" window are reset to the value of the last QSO previously completed (in a situation without any CAT). In my opinion, that makes little sense. The frequency field should not auto-change back. And, once at it, the mode, both RSTs, and pwr are also better left alone, at least in my opinion.
Here is a story that actually happened to me last Saturday:
I'm operating a QRP multiband rig (blue cool radio, in my case) with no CAT control and use cqrlog for logging. I operate on 20 m and make a few QSOs. I don't bother to have the precise frequency in my log, the "14.000" default is fine for me.
I decide to switch from 20 m to 40 m. Antenna re-tuning, rig re-tuning, the usual band-change steps. As part of those, in cqrlog's "New QSO" window, field "frequency", I choose 7.000. I hear some station call CQ, so I enter their call into the "call" field. Alas, they don't hear me. So I delete their call and tune on. Find a second station calling CQ, enter their call in cqrlog, complete the QSO, and log it.
Expected outcome: The QSO is logged with frequency 7.000.
Outcome actually seen: The QSO is logged with frequency 14.000.
Workaround: I have started to log a "QSO" with "call" XXXXX after each band change. Those are easily deleted after end of operations.
The problem occurred with an older version, but was reproducible with 2.3.0.