Seeing new stuff in log after upgrading from 11 to 15

Hi,

After upgrade 11 -> 15 started to see these messages in hot standby log:

< 2024-05-15 17:20:24.164 CDT 151879 > LOG: restartpoint complete: wrote 296338 buffers (28.3%); 0 WAL file(s) added, 134 removed, 0 recycled; write=1619.469 s, sync=0.022 s, total=1619.539 s; sync files=1492, longest=0.002 s, average=0.001 s; distance=2195446 kB, estimate=4171347 kB
< 2024-05-15 17:20:24.164 CDT 151879 > LOG: recovery restart point at 17AB8/47000140
< 2024-05-15 17:20:24.164 CDT 151879 > DETAIL: Last completed transaction was at log time 2024-05-15 17:20:24.138362-05.
< 2024-05-15 17:20:24.167 CDT 151879 > LOG: restartpoint starting: wal

while running 11 the log was almost empty, and I did not modify verbosity settings...
Queston : are above harmless and just informational?
I checked the data and the data is definitely being replicated.

Thank you,
Dmitry