SaaS Application design

Hello,
Happy to to join this lovely forums and looking for your comments guys based on ur experience

We are developing our SaaS application and we came to a stage where we need your technical point of view.

This SaaS app has the same features and functions for all SaaS subscribers on PHP application layer. All subscribers MySQL database structures are identical since we are offering the same app to all of our subscribers.

As developers we came to the following options, which really needs your involvement to comment on it based on your experience;

1-Deploy a single database for all SaaS subscribers.

2-Deploy a single database for each subscriber.

The most important part is that all subscribers database will be queried by other users from the Internet when they visit our website. Those users are seeking some data, which will be published by the subscribers. The user will query all subscribers at the same time to get a result and then choose the preferred one.

We are wondering what would be the best option and what do you recommend and why to get in hands Scalability, Performance, and Security

Thank you so much and I appreciate your help

Best Regards,
Abdull