The reasons why eBay limits sales quota may include:

1. Account performance: eBay may limit sales quota based on account performance. For example, if the account's transaction rate of medium and bad reviews, dispute rate of items not matching descriptions, return rate of items not matching descriptions, and seller cancellation rate exceed the platform's threshold, the sales quota may be restricted.

2. Account history: eBay may consider the account's historical records, such as whether the account has a history of illegal operations, whether it has a history of bad transactions, etc. If the account has these problems, the sales quota may be restricted.

3. Logistics performance: eBay may limit sales quota based on the account's logistics performance. For example, if the account's delivery speed, return rate, etc. exceed the platform's threshold, the sales quota may be restricted.

4. Platform policy: eBay may limit sales quota based on the platform's policy. For example, some categories of goods may have special sales quota restrictions.

5. Account security: eBay may limit sales quota based on the security of the account. For example, if there are security risks in your account, such as being stolen, your sales quota may be restricted.

If your eBay account is restricted, you can try to contact eBay customer service to understand the specific reasons for the restriction and follow eBay's instructions to make improvements. If there is no problem with the account, eBay may gradually restore your sales quota.