Hey,
I will write it in order of appearance on the website. At first I'm on smartphone, so everything related to mobile version.
1) the header animation in height and background color is cool, but looks bugy/lagy if I scroll faster. I think it's because of some delays and so on instead of linear animation related to scroll height? 🤔
2) the wording "get started" related to "do something", like a quickstart guide for a framework. "Learn more" seems also not perfect for a link to "more about me".
3) mix of "we" and "I" - if you are alone behind this agency be proud of it and tell it like this. I know there was a trend of hiding behind a "we" to don't seem selfish or anything. But a lot of customers wonder who is "we" if they always/only talk to you.
4) "GET A WEBSITE" links to a page why JAMstack is cool - but nowhere any kind of request form. You should link to a page only with a sentence how long you need to respond and a contact form.
5) "THE JAMSTACK ADVANTAGE" seems to be on every page!? 🤔 On mobile this only bloats every page and doesn't clearly show what's really important/the content of this page.
6) "INTEGRATIONS" and "custom development" link to the same page. I would expect some examples what integrations could be. For example some cool APIs, a shop system, comments or whatever are common integrations are.