Don't switch between dark/light and light/dark text. It's jarring.
Your use of red/yellow/green/blue makes it look like you're ripping off Google. That's skeezy.
Your sizes and placements are all over the place. Tiny text. Giant text. GIANT screenshots. Shit thrown all over the place. The key to good design is planning. It looks like you didn't have a plan.
On content:
Phrases like "Empowering people", "Uniting communities", and "help people get things done in the real world" are all meaningless fluff that tell me literally nothing about what service or product you provide. The very first thing I see when loading your page should be a PRECISE statement of exactly what you do for me.
On tech:
Navigation performance is terrible and things are interactive for no reason. I don't need or want a rendered globe that spins around when I drag on it. But if you're going to do it anyway, at least make sure that it's not super janky.
There's some extreme layout pop when mousing around your navbars.
On advice:
Practically speaking, nobody cares about someone else's shitty side project. If you want it to look nice, hire someone with even a modicum of aesthetic sense.
I'm stuck with slow internet for now and can say this: The images on the site are far too large in terms of file size. I had to download over 10 MB to view the homepage according to Firefox's dev tools.
https://qbix.com/img/welcome/communities.png is a photo encoded as a PNG. That's a bad idea that will lead to unnecessarily large file sizes (1.9 MB). Use JPG or a newer format like WebP. Better yet, eliminate this image entirely as it's a boring stock image that adds nothing.
https://qbix.com/img/mainVideo.png is also huge (2.1 MB) but doesn't need to be. If it's a video frame then why make it 2,654 px by 1,490 px?
Remove all the boxes and drop-shadows. They look very outdated. Use full-width for the hero and remove the whole box-shadow around the lower sections.
Now using space to separate the sections. For example, adding a vertical padding of 64px to the "We build apps" section automatically makes it look like a Stripe-like site. An example: https://onepagelove.com/smash-lite
Use bullet points:
On the "Are you still sending emails?" section just use bullet points. Remove the border and background color on that table with odd-even colors. And add actual bullets. You already used <ul> and <li>, now let people know that those are bullet points. Add some padding between each bullet point.
HTML bullet points already make it better to read. If you want to look cute, use bullet point images that catch the eye. Similar to how this template does: https://onepagelove.com/devbook
Use visual hierarchy:
For the section titles, use a larger font size, like 36px. Add some padding to the bottom to make it stand apart from the text. Users will use this to their advantage to scan your page.
You're already using bold for the bullet point titles, so you're aware that they're important. Make them pop more by putting the title in its own line and make it a bit bigger. I'd try to use less copy. Drop the effect that collapses the text when you click it.
Be consistent:
Designers are very consistent when it comes to spacing. Try to stick to multiples of 8px: 8px, 16px, 24px, 36px, 48px, 64px. Try to avoid using multiple fonts and colors for things that are in the same hierarchy.
I think you get the gist. Alternatively, just get a free template like the ones I linked, it's much easier than designing things from scratch.
The good, the bad and the ugly. We want to make it not look like a side project by open source guys but actually make people excited like Stripe does.
Only thing I ask is be extremely specific and give immediately actionable advice. We support desktop and mobile browsers.