I have a problem with Safari on different macOS versions. Is there any information from which version Safari doesn't support 32 bit architecture? Like Firefox (from v.56) and Chrome (from v.74) on macOS.
According to Wikipedia - https://en.wikipedia.org/wiki/Safari_(web_browser)#64-bit_builds - Safari has been 64-bit since Snow Leopard OS X 10.6 in 2009, which would be Safari 5, [around the same time they stopped supporting Windows.]
All Macs since then have been 64-bit capable, but until Catalina have been backwards compatible with 32-bit applications.
The last OS X to be capable of running on 32-bit architecture was also Snow Leopard, 10.6
The App Store will only offer you builds of Safari compatible with your Mac's hardware & OS
Safari 11 - 10.11 to 10.12
Safari 12 - 10.12 to 10.13
Safari 13 - 10.13 to 10.15
Safari 14 - macOS 11 [backwards compatibility currently unknown]