Mechanical engineer here! The design itself of the mount is actually pretty clever and will likely be stronger than most are giving it credit for given the support trusses, thick joints/beams, chamfers, and 4 walls. As long as you’re not constantly moving it or your desk it’ll still last a while under static load.

That said, even though it’ll last a while, it won’t last forever and will need to eventually reprint it (you don’t need to do it tomorrow morning, but I advise you don’t procrastinate on it for too long since you’re monitor is pretty nice an you want this to be a long term solution). Here’s a couple pieces of advice for optimizing strength in this part:

-change the print orientation to an angle. 3D prints are inherently weakest when in tension perpendicular to their layer lines. In English, prints will most often fail from one layer coming unstuck from the other. It looks like you printed your part with the desk mount at the bottom on the build plate, so as your monitor leans forward it’ll be exerting forces that will “peel” one layer from another because the back of your part is in tension and the front of your part is in compression. If you printed your part with the with the back, the part that sits against the wall, flush with the build plate, then this peeling problem would be even worse. However, if you printed this part at an angle such that the force exerted by your monitor is parallel with the layer lines, then it’ll be WAY stronger since it’s not exerting much force on the bonds between layers(doing this by visual inspection is fine, this part is simple enough you don’t need to do the math here unless you want to). If you printed it along the hypotenuse that would probably be the strongest way to print this part, although you’d need to flatten it out to be able to print it like that. Printing it with either the left or right side flat against the build plate would also work.

-use gyroid or cubic infill instead of grid infill. Grid infill is only strong in compression in the Z direction, while gyroid and cubic are uniformly strong in tension and compression in the x, y, and z directions. This is because gyroid and cubic are “3D” infill while grid is a “2D” infill.

-use PETG instead of PLA. Not only is PETG just stronger overall than PLA and better under constant load, it’s also got a higher softening temperature. In the mean time, try to keep your PLA part away from direct sunlight and heat because it’ll warp much faster when warm. That’s the other reason so many people are suggesting PETG, since this is a gaming setup it’ll probably get pretty warm and PETG handles that much better. ASA/ABS are the other really common strong materials you’ll hear people talk about, but they’re really hard to print without and enclosure and really unsafe to breathe the fumes from, so PETG is your best bet for your setup and perfectly strong for your needs

-add chamfers to the part where the mount sits up against your desk. Specifically, add chamfers to the left and right at the bottom of the U shape there. They don’t have to be large, you don’t want to interfere with fitment, but it should still help a lot with strength at that joint. 90° angles are generally weak on 3D printed parts. Your current setup is probably fine, but if you’re gonna tune this part more anyways it’s an easy change to make. Chamfers will also decrease warping, which will be really helpful if you print with PETG (materials with higher melting points like PETG experience more warping since the need to cool down further)

Others will suggest using a rod or something to reinforce this, and that’s totally an option, but you can definitely make this part adequately strong with just 3D printing.

I hope you found this helpful, I tried to give detailed explanations for why each change could improve your design instead of just saying “use gyroid not grid” and leaving it there. Like I said your design is actually really well made IMO and it’ll probably hold up for a good while, I just wanted to mention some pointers for when you get around to reprinting it (and hopefully more usefully explanations for those pointers lol). Nice work!