Do search engines like big changes to websites?

On the 22nd of May I made big production changes to my already-existing website, which included subscriptions, payments, paywalls, etc. Two days later I get my first paying customer, and seven days after that I get another paying customer - and no, these weren't people I know!

Since then I haven't made any major changes to the website, I've seen organic traffic decrease gradually, and I haven't received any other paying customers.

I'm sure that it is just a coincidence, but it does seem strange.

I haven't started marketing the site in any way yet, so I was thrilled that these people somehow found my site and wanted to pay, but two paying customers within a week of launching payments and nothing in the following two-and-a-bit months seems odd.

It is just coincidence or do search engines like change?