[OJS 3.2.1.4] Database connection failed

Hi,

For 2 days, these errors have been appearing which knock down my platform.

[Mon Nov 08 15:45:35.737333 2021] [php7:notice] [pid 10280] [client 181.206.72.185:59029] ojs2: Database connection failed!, referer: https://www.google.com/
[Mon Nov 08 15:45:35.916818 2021] [php7:notice] [pid 10273] [client 201.203.117.5:32664] ojs2: Database connection failed!, referer: https://scholar.google.es/
[Mon Nov 08 15:45:37.378351 2021] [php7:notice] [pid 10281] [client 45.164.236.16:14304] ojs2: Database connection failed!, referer: https://scholar.google.com.mx/
[Mon Nov 08 15:45:38.824949 2021] [php7:notice] [pid 10257] [client 177.98.208.238:52163] ojs2: Database connection failed!
[Mon Nov 08 15:45:40.976626 2021] [php7:notice] [pid 9910] [client 40.77.167.28:37249] ojs2: Database connection failed!
[Mon Nov 08 15:45:41.406045 2021] [php7:notice] [pid 10282] [client 181.129.248.139:57722] ojs2: Database connection failed!, referer: https://www.google.com/
[Mon Nov 08 15:45:41.418550 2021] [php7:notice] [pid 10289] [client 201.203.117.5:32671] ojs2: Database connection failed!, referer: https://scholar.google.es/
[Mon Nov 08 15:45:42.332084 2021] [php7:notice] [pid 10287] [client 186.185.28.16:18928] ojs2: Database connection failed!, referer: https://www.google.com/
[Mon Nov 08 15:45:45.450610 2021] [php7:notice] [pid 10103] [client 190.156.100.29:59359] ojs2: Database connection failed!, referer: https://www.google.com/
[Mon Nov 08 15:45:46.265008 2021] [php7:notice] [pid 10273] [client 189.252.173.71:54353] ojs2: Database connection failed!, referer: https://www.google.com/

What could it be:

Hi,

Someone who can help me with this, what could be or what could I do to solve this.

Could you give some more detailed information:
Which OJS version are you using?
Your PHP version?
What changes have you made recently?
Your hosting company may have made an infrastructure change.