Macs do not do well in a “*********** install” environment. What you are attempting is unsupported. Your 2014 MacBook Pro is not a PC. It does not support any kind of hard drive upgrade.
What happened to the SSD that it came with? Put that back in and install Catalina.
Consider the reverse scenario. Suppose we were on a PC-focused discussion forum. You were trying to get a new SSD installed in your PC and you were having some issues with firmware updates. What would that discussion look like? Would you be expected to mention the make and model of the SSD you were attempting to install? Would you be expected to mention the type of PC/motherboard and firmware versions of the machine you were attempting to install it into? If I chimed in with something along the lines of “LOL! Get a Mac!”, would that be considered helpful and constructive?
Why should this forum and Macs be considered any differently? What you are describing is not supported by Apple. What you are attempting is rarely done by Mac users. The few people who do attempt it use very specific parts from specific vendors that are known to work. Those parts come with very specific installation requirements. I have never seen anyone attempt to involve PCs. Most of these upgrades are uneventful, aside from a greater occurrence of kernel panics later on. There are no partition issues.
So, if you want to get this SSD working in this Mac, I suggest you meet us halfway. Describe exactly what hardware you are attempting to install. Explain why you haven’t simply upgraded the operating system first and then replaced the drive. Maybe explain why you aren’t using the original SSD that it came with. I strongly suspect that merely attempting to provide this information will allow you to figure out what is going wrong and resolve the problem yourself with no further consternation.