How to determine the type of encryption?

Question

Encryption

Is there an initial variant
and a final encrypted one,
what is between them?

Qq12345!
Md9EHgcJL8I=

How to get 2 from option 1

Answer 1

it is impossible to determine the type of encryption
without direct instructions

Answer 2

You can try to guess, but it can take time tending to infinity.

Answer 3

It looks more like hashing, the output of which is 64 bits. Or checksum.
The result is Base64 encoded.

Answer 4

1. Now - this is the usual arbitrary one-sided mapping of two lines to each other.
2. The original algorithm can only be restored by debugging the application while executing its instructions (according to the algorithm in the source code).
Any other options are not possible.