I have 4 iPad pros (not counting the old lightning ones), an A12x with 4GB RAM, an A12X with 6, a M1 with 8 and a M1 with 16. The 4GB one refreshes all the time, sometimes even with 1 tab open. The 6, 8 and 16 GB RAM ones are very similar, they refresh given enough tabs and time, but not always, sometimes they can keep several tabs open for days. I have heard different experience, but that's mine, not much difference for Safari if you have at least 6GB RAM.My M1 will regularly refresh Safari with only 4 tabs open. Only other apps I regularly use are Mail, Netnewswire, and eBay.
That doesn't make me want to get the 16GB RAM M4, but maybe I should wait Apple Intelligence to see if that impacts RAM...