A total of 2 reviews of this product on Reddit.
You can get KVMs but as you saw their reviews aren’t great and they usually have limitations like 4k30. Also I’m not sure if you’re going to find one for three monitors. Apparently some KVMs let you link them together for more ports (https://www.amazon.com/ATEN-2-Port-DisplayPort-Display-Switch/dp/B07KJV6Y7P) but that gets expensive.
What I did was just connect the monitor to both the PC and dock, and use the monitor input to switch the video. I used a USB switch for all the peripherals. I only am switching one monitor, though, so using the monitor inputs is no big deal.
That would be a KVM switch. note that there are several models, and some use HDMI, some use DP, some only support 60 FPD. Something like this: https://www.amazon.com/dp/B07KJV6Y7P/ref=cm_sw_r_cp_awdb_imm_t1_cAs6Fb3AQW90C