[BUG] Incorrect date option is selected for delivery after reloading the checkout page

[YachYaroslav]

To Reproduce
Steps to reproduce the behavior:

1. Go to 'Admin' -> 'Stores' -> 'Configuration' -> 'Sales' -> 'PostNL'
2. Open 'Delivery' -> 'Delivery Days' config section and set 'Maximum number of delivery days' to 14 (instead of 7 default).
3. Save config and clear the caches.
4. Go to frontend checkout page.
5. Fill the address of the Netherlands (e.g. Street Address - Weena XXXX, City - Rotterdam, Zip/Postal Code - 3013AL).
6. Click on 'PostNL' shipping method and select Monday (the earliest one / top one).
7. Refresh the checkout page (F5).
8. Scroll down to 'PostNL' shipping method.

Expected result
The same date option is selected (Monday 12-08-2024).

Actual result
The week after date option is selected (Monday 19-08-2024).

Workaround
None

Screenshots

Before reload (Monday 12-08-2024 is selected):

After reload (incorrect Monday 19-08-2024 is selected):

• Magento version (pure with only tig/postnl-magento2): 2.4.6
• PHP version: 8.1.3
• TIG PostNL version: 1.15.2

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Also the same issue is reproducible on a highly customized Magento (with Swissup_Firecheckout and many custom modules):

• Magento version: 2.4.3-p3
• PHP version: 7.4.28
• TIG PostNL version: 1.15.2

[JorisPostNL]

Hi @YachYaroslav, thank you for reporting this issue.

Unfortunately the issue you mention is caused by the way the Magento2 framework itselfs handles the check-out data, and not by our plug-in. We have investigated this issue in the past and came to the conclusion we could not fix this issue without working on Magento2 itself rather than our plug-in. This means that unfortunately there is nothing we can do about this problem at this moment.

Note: since all three issues you posted concern the same root cause I will copy and paste this answer in all three tickets, so it's clear for other visitors what the outcome of your report was.

Kind regards
Joris - PostNL