Recover OpenCore boot loader after Linux installation

Hey reddit!

I noticed that macOS 14.5 on my macbook pro 2015 13" works slower than I expected, and decide to install Ubuntu 24.04 to compare the performance. Guess what, it works quicker, my metric is the feedback on the webapp, for instance when I type in text in Slack (slack is not good benchmark, but this is what I have to use in my work regulary and slow feedback burned out me).

But sometimes I have to use macOS as well. I tried to boot back, but for some reason I see the black screen and link support.apple.com/startup. I read this guide, but I didn't find anything useful. I think grub just override the bootloader somehow. Is there a tool to recover the bootloader, like bootmgr on Windows or grub on Linux? Any suggestion on how I could recover after this? I asked GPT4o, it didn't help as well.

Thanks!

Author: @r2d2cyborg