What do you mean by "page speed" is this an internal tool or external tool measuring.
Make sure you are not confusing store ranking metric vs real perfomance audit tests.
Read or reread the free manual: https://help.shopify.com/en/manual/online-store/store-speed/speed-report
Store performance ranking is you vs others stores like yours. So a drop off just indicates your competitors are improving and you're staying the same not necessarily that store "speed" is getting slower for actual customers.
If you need consulting on this to understand what is going on or get an audit with actionable items then contact me by mail for services.
ALWAYS please provide context, examples: store url, theme name, post url(s) , or any further detail in ALL correspondence.
Contact info in signature.
Thanks for reaching out to the community!
Here are some suggestions for you to optimize the speed of your website:
Hope it helps!
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