Currently the artificer infusion choices are level locked when they should not be.

With the current implementation at level 6, you can only have 4 level 2 infusions, and 2 level 6 infusions. However according to RAW there is no such limitation, and as you level, should be able to switch over level 2 infusions to level 6 infusions. So at level 6 you should technically be able to have 3 level 2 infusions, and 3 level 6 infusions. At level 7 2 level 2 infusions, 4 level 6 infusions, etc. Table should look something like this

+----------------+----------------+-----------------------+-----------------------+------------------------+------------------------+
| Artificer Level| Infusions Known| Level 2 Infusions Max | Level 6 Infusions Max | Level 10 Infusions Max | Level 14 Infusions Max |
+----------------+----------------+-----------------------+-----------------------+------------------------+------------------------+
| 2              | 4              | 4                     | 0                     | 0                      | 0                      |
| 3              | 4              | 4                     | 0                     | 0                      | 0                      |
| 4              | 4              | 4                     | 0                     | 0                      | 0                      |
| 5              | 4              | 4                     | 0                     | 0                      | 0                      |
| 6              | 6              | 6                     | 3                     | 0                      | 0                      |
| 7              | 6              | 6                     | 4                     | 0                      | 0                      |
| 8              | 6              | 6                     | 5                     | 0                      | 0                      |
| 9              | 6              | 6                     | 6                     | 0                      | 0                      |
| 10             | 8              | 8                     | 8                     | 2                      | 0                      |
| 11             | 8              | 8                     | 8                     | 3                      | 0                      |
| 12             | 8              | 8                     | 8                     | 4                      | 0                      |
| 13             | 8              | 8                     | 8                     | 5                      | 0                      |
| 14             | 10             | 10                    | 10                    | 6                      | 2                      |
| 15             | 10             | 10                    | 10                    | 7                      | 3                      |
| 16             | 10             | 10                    | 10                    | 8                      | 4                      |
| 17             | 10             | 10                    | 10                    | 9                      | 5                      |
| 18             | 12             | 12                    | 12                    | 10                     | 6                      |
| 19             | 12             | 12                    | 12                    | 11                     | 7                      |
| 20             | 12             | 12                    | 12                    | 12                     | 8                      |
+----------------+----------------+-----------------------+-----------------------+------------------------+------------------------+

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“Infusions Known

When you gain this feature, pick four artificer infusions to learn, choosing from the “Artificer Infusions” section at the end of the class’s description. You learn additional infusions of your choice when you reach certain levels in this class, as shown in the Infusions Known column of the Artificer table.

Whenever you gain a level in this class, you can replace one of the artificer infusions you learned with a new one.”