“Skipping bootstrap because certbot-auto is deprecated on this system.” on Debian

Question

I am on Debian 10. I try to follow this tutorial to set Let’s Encrypt on a Shared web hosting service. So, I need to do lets-encrypt’s manipulation locally. BTW, I did it many times before without problem.

Now, when I make:

./letsencrypt-auto-source/letsencrypt-auto certonly --manual \
  --manual-public-ip-logging-ok \
  --email [email protected] \
  --agree-tos \
  --domain example.com \
  --domain www.example.com \
  --rsa-key-size 2048

I get the following error message:

Skipping bootstrap because certbot-auto is deprecated on this system.
./letsencrypt-auto-source/letsencrypt-auto has insecure permissions!
To learn how to fix them, visit https://community.letsencrypt.org/t/certbot-auto-deployment-best-practices/91979/
Your system is not supported by certbot-auto anymore.
Certbot cannot be installed.
Please visit https://certbot.eff.org/ to check for other alternatives.

BTW, I follow the given link and did all the asked commands:

# snap install core; snap refresh core
snap "core" is already installed, see 'snap help refresh'
snap "core" has no updates available
# snap install --classic certbot
snap "certbot" is already installed, see 'snap help refresh'
# ln -s /snap/bin/certbot /usr/bin/certbot

Also, certbot is not installed by Debian’s native package manager:

# aptitude show certbot
Package: certbot
Version: 1.12.0-2
State: not installed (configuration files remain)

Now, I tried again the Lets-encrypt command bellow, and still get:

Skipping bootstrap because certbot-auto is deprecated on this system.
./letsencrypt-auto-source/letsencrypt-auto has insecure permissions!
To learn how to fix them, visit https://community.letsencrypt.org/t/certbot-auto-deployment-best-practices/91979/
Your system is not supported by certbot-auto anymore.
Certbot cannot be installed.
Please visit https://certbot.eff.org/ to check for other alternatives.

So, what to do? Why Lets-encrypt still tell me certbot not up to day when I do everything he ask?