The good news is that COVID-era entry rules have been dropped by the overwhelming majority of countries, and routine tourist travel no longer involves tests, vaccination proof or quarantine in almost all destinations. Most of the dashboards and rule trackers from that period have been retired too, which is exactly why the remaining right answer is to check current official sources rather than memories or old blog posts.
Your verification checklist close to departure: the destination country's official immigration or health ministry website, your own government's travel advisory page for that country, and your airline's travel requirements page, since carriers enforce whatever documentation rules remain.
If you still hold vaccination certificates, keep digital copies; they occasionally remain useful for specific situations. And regardless of rules, flying while actively ill is worth avoiding for your own sake, and travel insurance that covers medical care and trip disruption from illness now does the practical job that entry rules once tried to do.