Centos 7.9 python3 cant find modules installed via yum

My stub python3 program cannot find the "pytz" module:

[me@mybox]$ uname -a
Linux portal2 3.10.0-1160.53.1.el7.x86_64 #1 SMP Fri Jan 14 13:59:45 UTC 2022 x86_64 x86_64 x86_64 GNU/Linux
[me@mybox]$ cat /etc/redhat-release 
CentOS Linux release 7.9.2009 (Core)
[me@mybox]$ 
[me@mybox]$ cat t2b.py
#!/usr/bin/env python3

import sys
import datetime
import time
import pytz

from datetime import datetime, timezone, tzinfo


[me@mybox]$  ./t2b.py 
Traceback (most recent call last):
  File "./t2b.py", line 6, in <module>
    import pytz
ModuleNotFoundError: No module named 'pytz'
[me@mybox]$ 

"yum" on my Centos 7 box provides the 'pytz' module, so I installed it (many lines deleted):

[root@mybox ~]# yum install pytz
Loaded plugins: fastestmirror, langpacks
Determining fastest mirrors
.     .     .     .     .
Resolving Dependencies
--> Running transaction check
---> Package pytz.noarch 0:2016.10-2.el7 will be installed
--> Finished Dependency Resolution
.     .     .     .     .
Dependencies Resolved
.     .     .     .     .
Installing:
 pytz           noarch           2016.10-2.el7             base            46 k
.     .     .     .     .
Installed:
  pytz.noarch 0:2016.10-2.el7

Complete!
[root@mybox ~]# 

But after this, my stub program failed in the identical manner! As far as it was concerned, there was still " No module named 'pytz' ", even after a reboot and logging back in.

It was not until after I installed the 'pytz' module via 'pip3' that t2b.py could find it.

[root@portal2 ~]# pip3 install pytz
WARNING: Running pip install with root privileges is generally not a good idea. Try `pip3 install --user` instead.
Collecting pytz
  Downloading https://files.pythonhosted.org/packages/d3/e3/d9f046b5d1c94a3aeab15f1f867aa414f8ee9d196fae6865f1d6a0ee1a0b/pytz-2021.3-py2.py3-none-any.whl (503kB)
    100% |████████████████████████████████| 512kB 2.0MB/s 
Installing collected packages: pytz
Successfully installed pytz-2021.3
[root@portal2 ~]#

[kurt@mybox ]$ ./t2b.py 
[kurt@mybox ]$

As far as possible I'd like to uniformly maintain installed software via "yum". My question is why will this not work for this python3 module, and/or what additional steps do I have to take for the process to work properly?

Nothing makes the obvious answers pop up in front of you like going through the work of asking the question. It appears that I installed 'pytz' for python2:

[root@mybox ~]# yum list all | grep pytz
pytz.noarch                                2016.10-2.el7          @base         
python36-pytz.noarch                       2017.2-3.el7           epel          
rh-python38-python-pytz.noarch             2019.3-4.el7           centos-sclo-rh
[root@pmybox ~]# python3 -V
Python 3.6.8
[root@mybox ~]# 

It is unsurprising that my little python3 program could not find that. Most likely I should have installed 'python36-pytz', and my program would have found it.